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- // Copyright 2017 The go-ethereum Authors
- // This file is part of the go-ethereum library.
- //
- // The go-ethereum library is free software: you can redistribute it and/or modify
- // it under the terms of the GNU Lesser General Public License as published by
- // the Free Software Foundation, either version 3 of the License, or
- // (at your option) any later version.
- //
- // The go-ethereum library is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- // GNU Lesser General Public License for more details.
- //
- // You should have received a copy of the GNU Lesser General Public License
- // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
- package ethash
- import (
- "bytes"
- "context"
- crand "crypto/rand"
- "encoding/json"
- "errors"
- "math"
- "math/big"
- "math/rand"
- "net/http"
- "runtime"
- "sync"
- "time"
- "github.com/ethereum/go-ethereum/common"
- "github.com/ethereum/go-ethereum/common/hexutil"
- "github.com/ethereum/go-ethereum/consensus"
- "github.com/ethereum/go-ethereum/core/types"
- )
- const (
- // staleThreshold is the maximum depth of the acceptable stale but valid ethash solution.
- staleThreshold = 7
- )
- var (
- errNoMiningWork = errors.New("no mining work available yet")
- errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
- )
- // Seal implements consensus.Engine, attempting to find a nonce that satisfies
- // the block's difficulty requirements.
- func (ethash *Ethash) Seal(chain consensus.ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
- // If we're running a fake PoW, simply return a 0 nonce immediately
- if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
- header := block.Header()
- header.Nonce, header.MixDigest = types.BlockNonce{}, common.Hash{}
- select {
- case results <- block.WithSeal(header):
- default:
- ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
- }
- return nil
- }
- // If we're running a shared PoW, delegate sealing to it
- if ethash.shared != nil {
- return ethash.shared.Seal(chain, block, results, stop)
- }
- // Create a runner and the multiple search threads it directs
- abort := make(chan struct{})
- ethash.lock.Lock()
- threads := ethash.threads
- if ethash.rand == nil {
- seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
- if err != nil {
- ethash.lock.Unlock()
- return err
- }
- ethash.rand = rand.New(rand.NewSource(seed.Int64()))
- }
- ethash.lock.Unlock()
- if threads == 0 {
- threads = runtime.NumCPU()
- }
- if threads < 0 {
- threads = 0 // Allows disabling local mining without extra logic around local/remote
- }
- // Push new work to remote sealer
- if ethash.remote != nil {
- ethash.remote.workCh <- &sealTask{block: block, results: results}
- }
- var (
- pend sync.WaitGroup
- locals = make(chan *types.Block)
- )
- for i := 0; i < threads; i++ {
- pend.Add(1)
- go func(id int, nonce uint64) {
- defer pend.Done()
- ethash.mine(block, id, nonce, abort, locals)
- }(i, uint64(ethash.rand.Int63()))
- }
- // Wait until sealing is terminated or a nonce is found
- go func() {
- var result *types.Block
- select {
- case <-stop:
- // Outside abort, stop all miner threads
- close(abort)
- case result = <-locals:
- // One of the threads found a block, abort all others
- select {
- case results <- result:
- default:
- ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "local", "sealhash", ethash.SealHash(block.Header()))
- }
- close(abort)
- case <-ethash.update:
- // Thread count was changed on user request, restart
- close(abort)
- if err := ethash.Seal(chain, block, results, stop); err != nil {
- ethash.config.Log.Error("Failed to restart sealing after update", "err", err)
- }
- }
- // Wait for all miners to terminate and return the block
- pend.Wait()
- }()
- return nil
- }
- // mine is the actual proof-of-work miner that searches for a nonce starting from
- // seed that results in correct final block difficulty.
- func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
- // Extract some data from the header
- var (
- header = block.Header()
- hash = ethash.SealHash(header).Bytes()
- target = new(big.Int).Div(two256, header.Difficulty)
- number = header.Number.Uint64()
- dataset = ethash.dataset(number, false)
- )
- // Start generating random nonces until we abort or find a good one
- var (
- attempts = int64(0)
- nonce = seed
- )
- logger := ethash.config.Log.New("miner", id)
- logger.Trace("Started ethash search for new nonces", "seed", seed)
- search:
- for {
- select {
- case <-abort:
- // Mining terminated, update stats and abort
- logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
- ethash.hashrate.Mark(attempts)
- break search
- default:
- // We don't have to update hash rate on every nonce, so update after after 2^X nonces
- attempts++
- if (attempts % (1 << 15)) == 0 {
- ethash.hashrate.Mark(attempts)
- attempts = 0
- }
- // Compute the PoW value of this nonce
- digest, result := hashimotoFull(dataset.dataset, hash, nonce)
- if new(big.Int).SetBytes(result).Cmp(target) <= 0 {
- // Correct nonce found, create a new header with it
- header = types.CopyHeader(header)
- header.Nonce = types.EncodeNonce(nonce)
- header.MixDigest = common.BytesToHash(digest)
- // Seal and return a block (if still needed)
- select {
- case found <- block.WithSeal(header):
- logger.Trace("Ethash nonce found and reported", "attempts", nonce-seed, "nonce", nonce)
- case <-abort:
- logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
- }
- break search
- }
- nonce++
- }
- }
- // Datasets are unmapped in a finalizer. Ensure that the dataset stays live
- // during sealing so it's not unmapped while being read.
- runtime.KeepAlive(dataset)
- }
- // This is the timeout for HTTP requests to notify external miners.
- const remoteSealerTimeout = 1 * time.Second
- type remoteSealer struct {
- works map[common.Hash]*types.Block
- rates map[common.Hash]hashrate
- currentBlock *types.Block
- currentWork [4]string
- notifyCtx context.Context
- cancelNotify context.CancelFunc // cancels all notification requests
- reqWG sync.WaitGroup // tracks notification request goroutines
- ethash *Ethash
- noverify bool
- notifyURLs []string
- results chan<- *types.Block
- workCh chan *sealTask // Notification channel to push new work and relative result channel to remote sealer
- fetchWorkCh chan *sealWork // Channel used for remote sealer to fetch mining work
- submitWorkCh chan *mineResult // Channel used for remote sealer to submit their mining result
- fetchRateCh chan chan uint64 // Channel used to gather submitted hash rate for local or remote sealer.
- submitRateCh chan *hashrate // Channel used for remote sealer to submit their mining hashrate
- requestExit chan struct{}
- exitCh chan struct{}
- }
- // sealTask wraps a seal block with relative result channel for remote sealer thread.
- type sealTask struct {
- block *types.Block
- results chan<- *types.Block
- }
- // mineResult wraps the pow solution parameters for the specified block.
- type mineResult struct {
- nonce types.BlockNonce
- mixDigest common.Hash
- hash common.Hash
- errc chan error
- }
- // hashrate wraps the hash rate submitted by the remote sealer.
- type hashrate struct {
- id common.Hash
- ping time.Time
- rate uint64
- done chan struct{}
- }
- // sealWork wraps a seal work package for remote sealer.
- type sealWork struct {
- errc chan error
- res chan [4]string
- }
- func startRemoteSealer(ethash *Ethash, urls []string, noverify bool) *remoteSealer {
- ctx, cancel := context.WithCancel(context.Background())
- s := &remoteSealer{
- ethash: ethash,
- noverify: noverify,
- notifyURLs: urls,
- notifyCtx: ctx,
- cancelNotify: cancel,
- works: make(map[common.Hash]*types.Block),
- rates: make(map[common.Hash]hashrate),
- workCh: make(chan *sealTask),
- fetchWorkCh: make(chan *sealWork),
- submitWorkCh: make(chan *mineResult),
- fetchRateCh: make(chan chan uint64),
- submitRateCh: make(chan *hashrate),
- requestExit: make(chan struct{}),
- exitCh: make(chan struct{}),
- }
- go s.loop()
- return s
- }
- func (s *remoteSealer) loop() {
- defer func() {
- s.ethash.config.Log.Trace("Ethash remote sealer is exiting")
- s.cancelNotify()
- s.reqWG.Wait()
- close(s.exitCh)
- }()
- ticker := time.NewTicker(5 * time.Second)
- defer ticker.Stop()
- for {
- select {
- case work := <-s.workCh:
- // Update current work with new received block.
- // Note same work can be past twice, happens when changing CPU threads.
- s.results = work.results
- s.makeWork(work.block)
- s.notifyWork()
- case work := <-s.fetchWorkCh:
- // Return current mining work to remote miner.
- if s.currentBlock == nil {
- work.errc <- errNoMiningWork
- } else {
- work.res <- s.currentWork
- }
- case result := <-s.submitWorkCh:
- // Verify submitted PoW solution based on maintained mining blocks.
- if s.submitWork(result.nonce, result.mixDigest, result.hash) {
- result.errc <- nil
- } else {
- result.errc <- errInvalidSealResult
- }
- case result := <-s.submitRateCh:
- // Trace remote sealer's hash rate by submitted value.
- s.rates[result.id] = hashrate{rate: result.rate, ping: time.Now()}
- close(result.done)
- case req := <-s.fetchRateCh:
- // Gather all hash rate submitted by remote sealer.
- var total uint64
- for _, rate := range s.rates {
- // this could overflow
- total += rate.rate
- }
- req <- total
- case <-ticker.C:
- // Clear stale submitted hash rate.
- for id, rate := range s.rates {
- if time.Since(rate.ping) > 10*time.Second {
- delete(s.rates, id)
- }
- }
- // Clear stale pending blocks
- if s.currentBlock != nil {
- for hash, block := range s.works {
- if block.NumberU64()+staleThreshold <= s.currentBlock.NumberU64() {
- delete(s.works, hash)
- }
- }
- }
- case <-s.requestExit:
- return
- }
- }
- }
- // makeWork creates a work package for external miner.
- //
- // The work package consists of 3 strings:
- // result[0], 32 bytes hex encoded current block header pow-hash
- // result[1], 32 bytes hex encoded seed hash used for DAG
- // result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
- // result[3], hex encoded block number
- func (s *remoteSealer) makeWork(block *types.Block) {
- hash := s.ethash.SealHash(block.Header())
- s.currentWork[0] = hash.Hex()
- s.currentWork[1] = common.BytesToHash(SeedHash(block.NumberU64())).Hex()
- s.currentWork[2] = common.BytesToHash(new(big.Int).Div(two256, block.Difficulty()).Bytes()).Hex()
- s.currentWork[3] = hexutil.EncodeBig(block.Number())
- // Trace the seal work fetched by remote sealer.
- s.currentBlock = block
- s.works[hash] = block
- }
- // notifyWork notifies all the specified mining endpoints of the availability of
- // new work to be processed.
- func (s *remoteSealer) notifyWork() {
- work := s.currentWork
- // Encode the JSON payload of the notification. When NotifyFull is set,
- // this is the complete block header, otherwise it is a JSON array.
- var blob []byte
- if s.ethash.config.NotifyFull {
- blob, _ = json.Marshal(s.currentBlock.Header())
- } else {
- blob, _ = json.Marshal(work)
- }
- s.reqWG.Add(len(s.notifyURLs))
- for _, url := range s.notifyURLs {
- go s.sendNotification(s.notifyCtx, url, blob, work)
- }
- }
- func (s *remoteSealer) sendNotification(ctx context.Context, url string, json []byte, work [4]string) {
- defer s.reqWG.Done()
- req, err := http.NewRequest("POST", url, bytes.NewReader(json))
- if err != nil {
- s.ethash.config.Log.Warn("Can't create remote miner notification", "err", err)
- return
- }
- ctx, cancel := context.WithTimeout(ctx, remoteSealerTimeout)
- defer cancel()
- req = req.WithContext(ctx)
- req.Header.Set("Content-Type", "application/json")
- resp, err := http.DefaultClient.Do(req)
- if err != nil {
- s.ethash.config.Log.Warn("Failed to notify remote miner", "err", err)
- } else {
- s.ethash.config.Log.Trace("Notified remote miner", "miner", url, "hash", work[0], "target", work[2])
- resp.Body.Close()
- }
- }
- // submitWork verifies the submitted pow solution, returning
- // whether the solution was accepted or not (not can be both a bad pow as well as
- // any other error, like no pending work or stale mining result).
- func (s *remoteSealer) submitWork(nonce types.BlockNonce, mixDigest common.Hash, sealhash common.Hash) bool {
- if s.currentBlock == nil {
- s.ethash.config.Log.Error("Pending work without block", "sealhash", sealhash)
- return false
- }
- // Make sure the work submitted is present
- block := s.works[sealhash]
- if block == nil {
- s.ethash.config.Log.Warn("Work submitted but none pending", "sealhash", sealhash, "curnumber", s.currentBlock.NumberU64())
- return false
- }
- // Verify the correctness of submitted result.
- header := block.Header()
- header.Nonce = nonce
- header.MixDigest = mixDigest
- start := time.Now()
- if !s.noverify {
- if err := s.ethash.verifySeal(nil, header, true); err != nil {
- s.ethash.config.Log.Warn("Invalid proof-of-work submitted", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)), "err", err)
- return false
- }
- }
- // Make sure the result channel is assigned.
- if s.results == nil {
- s.ethash.config.Log.Warn("Ethash result channel is empty, submitted mining result is rejected")
- return false
- }
- s.ethash.config.Log.Trace("Verified correct proof-of-work", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)))
- // Solutions seems to be valid, return to the miner and notify acceptance.
- solution := block.WithSeal(header)
- // The submitted solution is within the scope of acceptance.
- if solution.NumberU64()+staleThreshold > s.currentBlock.NumberU64() {
- select {
- case s.results <- solution:
- s.ethash.config.Log.Debug("Work submitted is acceptable", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
- return true
- default:
- s.ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "remote", "sealhash", sealhash)
- return false
- }
- }
- // The submitted block is too old to accept, drop it.
- s.ethash.config.Log.Warn("Work submitted is too old", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
- return false
- }
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